Pittsburgh Mayor Bill Peduto has ordered flags flown at half-staff as authorities grieve the loss of a K-9 officer and moved to prosecute the suspect charged with fatally stabbing the animal.

Twenty-one-year-old John Lewis Rush was one of Allegheny County's most wanted fugitives when police say he stabbed the 8-year-old dog, Rocco, Tuesday night as officers tried to arrest him.

Police say Rush "lunged out from near a pillar and attacked K-9 Rocco," and used a pocket knife to stab the dog in the back. Three other officers were hurt in the struggle.

The dog survived surgery, but died at a veterinary hospital Thursday evening. The animal succumbed to his wounds and was not euthanized. He had showed signs of improvement but he suffered from additional bleeding and developed pneumonia, The Pittsburgh Post-Gazette reported.

"He fought as hard here as he did out on the field," one veterinarian said.

Police officers from the canine unit lined outside the hospital and played bagpipes as the dog was wheeled outside on an American-flag draped gurney.

Rush, who doesn't have a listed attorney, faces up to 7 years in prison if convicted of attacking the dog.